Liquid crystal display

ABSTRACT

Manufacture of a liquid crystal display is disclosed. The liquid crystal display includes a backlight unit, a backlight unit-side polarizing plate, and a liquid crystal cell held by two glass plates, the liquid crystal cell having an electrode, a liquid crystal layer, an alignment layer, and a color filter arranged between the glass plates. The liquid crystal display also includes a transparent front plate arranged at a side of the liquid crystal cell opposite to the backlight unit, a polarizing plate attached to the liquid crystal cell, and a transparent organic medium layer arranged between the front plate and the liquid crystal cell. Since the front plate is provided at the outermost surface of an image display portion, and the transparent organic medium is filled between the front plate and the liquid crystal module, it is possible to achieve an improvement in wear resistance and a reduction in reflectance.

CLAIM OF PRIORITY

The present application claims priority from Japanese Application JP2005-193296 filed on Jul. 01, 2005 and JP 2006-137216 filed on May 17,2006, the content of which is hereby incorporated by reference into thisapplication.

FIELD OF THE INVENTION

The present invention relates to a liquid crystal display, and moreparticularly to a liquid crystal display having a transparent frontplate arranged at an image display surface of the liquid crystaldisplay.

BACKGROUND OF THE INVENTION

In an image display device using liquid crystals, light from a lightsource is recognized as an image as the light passes through a liquidcrystal layer, a color filter, a polarizing plate, etc. In this case,the outermost surface of the image display device is the polarizingplate when the image display device is used as a personal computermonitor or as a liquid crystal television. In order to suppress surfacereflection, an anti-glaring membrane having small-size irregularities oran anti-reflecting membrane is formed over a surface of the polarizingplate. The polarizing plate is a thin film made of tri-acetyl cellulose.This film has a pencil hardness of about 2 to 3H.

Taking into the consideration the fact that, in the case of a liquidcrystal display used in a cellular phone, the liquid crystal displaycontinuously come into contact with a garment in a state of being putinto a pocket of the garment, a transparent resin plate made of acrylicresin or the like is provided on the polarizing plate, so that theliquid crystal display has an image display surface prevented fromcoming into direct contact with clothes, etc.

As mentioned above, the polarizing plate, which becomes the outermostsurface of the image display device when the image display device isused as a personal computer monitor or as a liquid crystal television,is constituted by a thin film made of tri-acetyl cellulose while havinga pencil hardness of about 2 to 3H. However, this film must have reducedwear resistance in order to form irregularities on the surface thereofin accordance with an anti-glaring process. For this reason, when thesurface of the film is wiped using a duster or the like at home, inorder to remove contaminants on the film surface, scratches are formedon the film surface if foreign matter of high hardness such as sand orsoil has been attached to the duster. That is, where the outermostsurface is provided by the polarizing plate, there is a problem of lowwear resistance.

Furthermore, there is a possibility that an object may be struck againstthe surface of the personal computer monitor or liquid crystaltelevision, even when the personal computer monitor or liquid crystaltelevision is disposed indoors. In addition, when a bowl, vase, or toyis struck against a glass plate arranged beneath the polarizing plate,the glass plate may be broken if the impact generated due to thestriking is excessive. This is because the glass plate has a thicknessof about 0.5 to 0.7 mm, even though the thickness depends on theproduct. In this connection, both personal computer monitor and liquidcrystal televisions have a tendency of an increased screen size.However, when the product has an increased screen size while maintainingthe thickness of the glass plate, it may be easily broken even by verysmall impact because of a reduction in impact resistance.

In the case of a cellular phone, the transparent resin plate of theoutermost surface thereof has a thickness of about 2 mm and is planar.Accordingly, even in a state in which the cellular phone is put into apocket of a jacket, scratches causing a degradation in visibility aredifficult to be formed on the outermost surface. In this case, however,since a gap is present between the transparent resin plate and thepolarizing plate, strong reflection of ambient objects to the imagedisplay surface occurs due to light reflection at the opposite surfacesof the transparent resin plate. For this reason, there is a problem of adegradation in visibility at a bright place.

In addition, two glass sheets, which are used to seal liquid crystalstherebetween in the manufacture of a liquid crystal panel, have a smallthickness of 0.5 to 0.7 mm. For this reason, the glass sheets may bebroken when they are held using a force higher than a required forceduring transportation or wiring procedures in each manufacturingprocess. Therefore, precision is required in the holding operationcarried out during the manufacture of the liquid crystal panel.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-mentionedproblems.

After reviewing various materials and plate configurations, theinventors found the facts that it is possible to achieve an improvementin wear resistance by providing a transparent plate at the outermostsurface, and to reduce reflection of ambient objects by filling atransparent organic medium in an air layer defined in between thepolarizing plate and the transparent plate, and thus, plugging the airlayer. The present invention has been made on the basis of these facts.

The inventors also found the fact that, even when the front plate ismade of organic resin, such as an acrylic plate, it is possible toachieve an improvement in wear resistance by providing ananti-reflecting membrane made of a material containing a silicon oxideof high hardness as the major component thereof. The present inventionhas been made on the basis of this fact.

The inventors also found that, when a polarizing plate is attached tothe front plate, an effect capable of adjusting the absorption axis ofthe polarizing plate can be obtained through a fine adjustment of theposition of the front plate. The present invention has been made on thebasis of this fact.

In addition, the inventors found that, since an anti-reflecting membranemade of silicon oxide exhibits a low liquid contact angle, namely, ahigh hydrophilicity, thereby improving the adherence of the polarizingplate, as compared to a transparent base plate, it is possible to reducegeneration of bubbles during the filling of the transparent organicmedium. The present invention has been made on the basis of this fact.

By virtue of the provision of the front plate, it is difficult to damagethe panel, itself even when it is more or less firmly held duringtransfer thereof. Accordingly, it is unnecessary to increase theaccuracy of the holding force of a holding system in the manufacturingapparatus.

The present invention provides the following aspects to achieve theabove aspects.

The first aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit; a polarizing plate attached to the liquid crystal cell; and atransparent organic medium layer arranged between the front plate andthe liquid crystal cell.

The second aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit; a transparent organic medium layer arranged between the frontplate and the liquid crystal cell; and a polarizing plate attached tothe front plate at a side of the transparent organic medium layer.

The third aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit; a polarizing plate attached to the liquid crystal cell; atransparent organic medium layer arranged between the front plate andthe liquid crystal cell; and an anti-reflecting membrane arranged at aside of the front plate opposite to the transparent organic mediumlayer.

The fourth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit; a transparent organic medium layer arranged between the frontplate and the liquid crystal cell; a polarizing plate attached to thefront plate at a side of the transparent organic medium layer; and ananti-reflecting membrane arranged at a side of the front plate oppositeto the transparent organic medium layer.

The fifth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane ateach of opposite surfaces of the transparent front plate; a polarizingplate attached to the liquid crystal cell; and a transparent organicmedium layer arranged between the front plate and the liquid crystalcell.

The sixth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane ateach of opposite surfaces of the transparent front plate; a transparentorganic medium layer arranged between the front plate and the liquidcrystal cell; and a polarizing plate attached to the front plate at aside of the transparent organic medium layer.

The seventh aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; apolarizing plate attached to the liquid crystal cell; and a transparentorganic medium layer arranged between the front plate and the liquidcrystal cell, wherein the backlight unit, the liquid crystal cell, andthe polarizing plate are held by a frame, wherein the front plate isattached to the polarizing plate such that the transparent organicmedium layer is interposed between the front plate and the polarizingplate.

The eighth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; apolarizing plate attached to the liquid crystal cell; and a transparentorganic medium layer arranged between the front plate and the liquidcrystal cell, wherein the backlight unit, the liquid crystal cell, thepolarizing plate, the transparent organic medium layer, and the frontplate are held by a frame.

The ninth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; atransparent organic medium layer arranged between the front plate andthe liquid crystal cell; and a polarizing plate attached to the frontplate at a side of the transparent organic medium layer, wherein thebacklight unit and the liquid crystal cell are held by a frame, whereinthe polarizing plate-side surface of the front plate is attached to theliquid crystal cell such that the transparent organic medium layer isinterposed between the polarizing plate-side surface and the liquidcrystal cell.

The tenth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; atransparent organic medium layer arranged between the front plate andthe liquid crystal cell; and a polarizing plate attached to the frontplate at a side of the transparent organic medium layer, wherein thebacklight unit, the liquid crystal cell, the transparent organic mediumlayer, the polarizing plate, and the front plate are held by a frame.

The eleventh aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; apolarizing plate attached to the liquid crystal cell; and a transparentorganic medium layer arranged between the front plate and the liquidcrystal cell, wherein the backlight unit, the liquid crystal cell, andthe polarizing plate are held by a frame, wherein the front plate isattached to the polarizing plate such that the transparent organicmedium layer is interposed between the front plate and the polarizingplate, wherein the frame and the front plate are fixed to each other.

The twelfth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further-comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; atransparent organic medium layer arranged between the front plate andthe liquid crystal cell, a polarizing plate attached to the front plateat a side of the transparent organic medium layer, wherein the backlightunit, the liquid crystal cell, and the backlight unit-side polarizingplate are held by a frame, wherein the polarizing plate-side surface ofthe front plate is attached to the liquid crystal cell such that thetransparent organic medium layer is interposed between the polarizingplate-side surface and the liquid crystal cell, wherein the frame andthe front plate are fixed to each other.

The thirteenth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; apolarizing plate attached to the liquid crystal cell; and a transparentorganic medium layer arranged between the front plate and the liquidcrystal cell, wherein the backlight unit is held by a frame, wherein theliquid crystal cell and the polarizing plate are held by the transparentorganic medium layer, wherein the front plate is attached to thepolarizing plate such that the transparent organic medium layer isinterposed between the front plate and the polarizing plate, the frameand the front plate are fixed to each other.

The fourteenth aspect is a liquid crystal display comprising a backlightunit, a backlight unit-side polarizing plate, and a liquid crystal cellheld by two glass plates, the liquid crystal cell having an electrode, aliquid crystal layer, an alignment layer, and a color filter arrangedbetween the glass plates, further comprising: a transparent front platearranged at a side of the liquid crystal cell opposite to the backlightunit, the transparent front plate having an anti-reflecting membrane; atransparent organic medium layer arranged between the front plate andthe liquid crystal cell; and a polarizing plate attached to the frontplate at a side of the transparent organic medium layer, wherein thebacklight unit is held by a frame, wherein the liquid crystal cell andthe backlight unit-side polarizing plate are held by the transparentorganic medium layer, wherein the polarizing plate-side surface of thefront plate is attached to the liquid crystal cell such that thetransparent organic medium layer is interposed between the polarizingplate-side surface and the liquid crystal cell, wherein the frame andthe front plate are fixed to each other.

The fifteenth aspect is the liquid crystal display according to any oneof the first through fourteenth aspects, wherein a driver for the liquidcrystal cell is arranged beneath the liquid crystal cell.

The sixteenth aspect is the liquid crystal display according to any oneof the first through fifteenth aspects, wherein the front plate has anarithmetic average roughness (Ra) of 10 nm or less.

The seventeenth aspect is the liquid crystal display according to anyone of the first through sixteenth aspects, wherein the transparentorganic medium layer has a thickness of 0.1 to 10 mm.

The eighteenth aspect is the liquid crystal display according to any oneof the first through seventeenth aspects, wherein the transparentorganic medium layer and the front plate have a refractive indexrelation satisfying the following equation:n ₀−0.2<n<n ₀+0.2wherein, “n” represents a refractive index of a member constituting thetransparent organic medium layer, and “n₀” represents a refractive indexof the front plate.

The nineteenth aspect is the liquid crystal display according to any oneof the first through eighteenth aspects, wherein the transparent organicmedium layer contains a compound capable of absorbing light in a visiblerange.

The twentieth aspect is the liquid crystal display according to any oneof the first through nineteenth aspects, wherein the compound capable ofabsorbing light in a visible range is a compound having a uniaxialanisotropy.

The twenty-first aspect is the liquid crystal display according to anyone of the third through twentieth aspects, wherein the anti-reflectingmembrane is made of silicon oxide particles and a binder, and theanti-reflecting membrane has pores formed in the anti-reflectingmembrane.

The twenty-second aspect is the liquid crystal display according to anyone of the third through twenty-first aspects, wherein theanti-reflecting membrane is made of silicon oxide particles and asilicon compound having a hydrolysable residue, and the anti-reflectingmembrane has pores formed in the anti-reflecting membrane.

The twenty-third aspect is the liquid crystal display according to anyone of the third through twenty-second aspects, wherein theanti-reflecting membrane is made of a compound having aperfluoropolyether chain, a perfluoroalkyl chain, or a fluoroalkyl chainat a surface of the compound.

The twenty-fourth aspect is a method for manufacturing a liquid crystaldisplay including a backlight unit, a backlight unit-side polarizingplate, and a liquid crystal cell held by two glass plates, the liquidcrystal cell having an electrode, a liquid crystal layer, an alignmentlayer, and a color filter arranged between the glass plates, atransparent front plate arranged at a side of the liquid crystal cellopposite to the backlight unit, a polarizing plate attached to theliquid crystal cell, and a transparent organic medium layer arrangedbetween the front plate and the liquid; crystal cell, the methodcomprising: treating a surface of the polarizing plate and a surface ofthe front plate contacting the transparent organic medium layer suchthat the surfaces have a water contact angle of 10° or less.

The twenty-fifth aspect is a method for manufacturing a liquid crystaldisplay including a backlight unit, a backlight unit-side polarizingplate, and a liquid crystal cell held by two glass plates, the liquidcrystal cell having an electrode, a liquid crystal layer, an alignmentlayer, and a color filter arranged between the glass plates, atransparent front plate arranged at a side of the liquid crystal cellopposite to the backlight unit, the transparent front plate having ananti-reflecting membrane at at least one surface of the transparentfront plate, a polarizing plate attached to the liquid crystal cell, anda transparent organic medium layer arranged between the front plate andthe liquid crystal cell, the method comprising: treating a surface ofthe polarizing plate and a surface of the front plate contacting thetransparent organic medium layer such that the surfaces have a watercontact angle of 10° or less.

The twenty-sixth aspect is a method for manufacturing a liquid crystaldisplay including a backlight unit, a backlight unit-side polarizingplate, and a liquid crystal cell held by two glass plates, the liquidcrystal cell having an electrode, a liquid crystal layer, an alignmentlayer, and a color filter arranged between the glass plates, atransparent front plate arranged at a side of the: liquid crystal cellopposite to the backlight unit, a transparent organic medium layerarranged between the front plate and the liquid crystal cell, and apolarizing plate attached to the front plate at a side of thetransparent organic medium layer, the method comprising: treating asurface of the polarizing plate and a surface of the front platecontacting the transparent organic medium layer such that the surfaceshave a water contact angle of 10° or less.

The twenty-seventh aspect is a method for manufacturing a liquid crystaldisplay including a backlight unit, a backlight unit-side polarizingplate, and a liquid crystal cell held by two glass plates, the liquidcrystal cell having an electrode, a liquid crystal layer, an alignmentlayer, and a color filter arranged between the glass plates, atransparent front plate arranged at a side of the liquid crystal cellopposite to the backlight unit, the transparent front plate having ananti-reflecting membrane at at least one surface of the transparentfront plate, a transparent organic medium layer arranged between thefront plate and the liquid crystal cell, and a polarizing plate attachedto the front plate at a side of the transparent organic medium layer,the method comprising: treating a surface of the polarizing plate and asurface of the front plate contacting the transparent organic mediumlayer such that the surfaces have a water contact angle of 10° or less.

It was confirmed that, when the front plate is provided on thepolarizing plate such that the transparent organic medium is interposedbetween the front plate and the polarizing plate, an improvement in wearresistance is obtained. Also, it was confirmed that a reduction inreflectance is caused only by the front plate. Also, it was confirmedthat a further reduction in reflectance is achieved in accordance withthe provision of the anti-reflecting membrane. In addition, it wasconfirmed that, when the polarizing plate is attached to the frontplate, easy axis adjustment of the polarizing plate is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, and other features and advantages of the presentinvention will become more apparent after reading the following detaileddescription when taken in conjunction with the drawings, in which:

FIGS. 1A and 1B are cross-sectional views schematically illustratingliquid crystal modules of liquid crystal displays according to a firstembodiment of the present invention, respectively;

FIGS. 2A and 2B are cross-sectional views schematically illustratingliquid crystal displays according to the present invention,respectively;

FIGS. 3A and 3B are cross-sectional views schematically illustratingliquid crystal modules of liquid crystal displays according to a secondembodiment of the present invention, respectively;

FIGS. 4A and 4B are cross-sectional views schematically illustratingliquid crystal modules of liquid crystal displays according to a thirdembodiment of the present invention, respectively;

FIGS. 5A and 5B are cross-sectional views schematically illustratingliquid crystal modules of liquid crystal displays according to a fourthembodiment of the present invention, respectively;

FIGS. 6A and 6B are views illustrating a polarizing plate/liquid crystalcell/polarizing plate/backlight unit part of a liquid crystal displayaccording to the present invention;

FIGS. 7A and 7B are views illustrating a polarizing plate/liquid crystalcell/polarizing plate/backlight unit/frame part of a liquid crystaldisplay according to the present invention;

FIGS. 8A and 8B are views illustrating a polarizing plate/liquid crystalcell/polarizing plate/backlight unit part of a liquid crystal displayaccording to the present invention;

FIG. 9 is a view illustrating a backlight unit part of a liquid crystaldisplay according to the present invention constituted by a polarizingplate/liquid crystal cell/polarizing plate/light emitting diodeconfiguration;

FIG. 10 is a view illustrating a structure of the light emitting diodeincluded in the backlight unit of the liquid crystal display accordingto the present invention;

FIGS. 11A and 11B are cross-sectional views schematically illustratingliquid crystal displays according to a fifth embodiment of the presentinvention, respectively;

FIGS. 12A and 12B are cross-sectional views schematically illustratingliquid crystal displays according to a sixth embodiment of the presentinvention, respectively;

FIGS. 13A and 13B are cross-sectional views schematically illustratingliquid crystal displays according to a seventh embodiment of the presentinvention, respectively;

FIGS. 14A and 14B are cross-sectional views schematically illustratingliquid crystal displays according to an eighth embodiment of the presentinvention, respectively;

FIG. 15 is a schematic view illustrating a process for filling atransparent organic medium in the manufacture of the liquid crystaldisplay according to the present invention;

FIG. 16 is a schematic view illustrating a transparent organic mediumlayer containing layer thickness control particles used in the presentinvention;

FIG. 17 is a schematic view illustrating a method for forming ananti-reflecting membrane used in the present invention;

FIG. 18 is a photograph showing the cross-section of the anti-reflectingmembrane used in the present invention; and

FIG. 19 illustrates graphs of element presence strengths of theanti-reflecting membrane used in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, the outline of the present invention will be described.

[A] Configuration of Image Display Device of Present Invention

The configuration of an image display device according to the presentinvention will be described with reference to FIGS. 1 to 14.

(1) Front Plate as Outermost Surface

Personal computer monitors or liquid crystal televisions, which arecurrently commercially available, have a structure which does notinclude a transparent organic medium layer 1 and a front plate 2 asshown in FIG. 1A. Referring to FIG. 1A, a structure is illustrated inwhich a polarizing plate 4, a liquid crystal cell 5, and anotherpolarizing plate 1 are arranged over a backlight unit 3 in an overlappedmanner. This structure is called a “liquid crystal module”. The liquidcrystal cell 5 is formed of a liquid crystal layer and a color filterlayer, which are arranged between, for example, a pair of transparentglass substrates, an electrode structure for applying an electric fieldto the liquid crystal layer, and various insulating films. The liquidcrystal cell having this structure, the polarizing plates varyingoptical characteristics, and the backlight unit functioning as a lightsource are bonded together to form an integrated structure, on which adriver IC for controlling LCD will be mounted. The resulting structureis called a “liquid crystal module”. In this case, low wear resistanceis exhibited because the outer polarizing plate forms the outermostsurface of the structure.

Therefore, in the present invention, a front plate is provided, as shownin FIG. 1A, to achieve an improvement in wear resistance. Also, atransparent organic medium is filled in a gap defined between the frontplate and the polarizing plate, to reduce reflection at the backside ofthe front plate.

The polarizing plate arranged between the liquid crystal cell and thetransparent organic medium layer is bonded to the liquid crystal cell inthe manufacturing procedure. In this case, however, it is necessary toachieve polarization axis alignment with a high accuracy. Moreover, thebonded polarizing plate cannot be re-bonded. However, when thepolarizing plate is bonded to the front plate while achievingpolarization axis alignment with a rough accuracy, there is an advantagein that it is possible to again perform polarization axis alignment uponmounting and fixing the front plate, and thus, to increase the accuracy.The reason why this possibility can be realized is that there is noproblem associated with display of an image even when the mountedposition of the front plate is slightly misaligned.

As shown in FIG. 2A or 2 b, a liquid crystal display can be manufacturedby mounting liquid crystal modules 6 each having the above-describedstructure, and mounting a power supply unit 7, a controller 8, a frontoutside frame 9, and a rear outside frame 10. For simplicity ofdescription, the following description will be given in conjunction withone liquid crystal module 6. FIG. 2A illustrates an example in which thefront plate has a size approximately equal to that of the liquid crystalcell. FIG. 2B illustrates an example in which there is no front outsideframe. In the case of FIG. 2B, there is no significant problem in termsof functions even when the front outside frame is used. Liquid crystalmodules, which are illustrated in FIGS. 3 to 5 and FIGS. 11 to 14 to bedescribed later, have the same configuration as that of FIG. 2A or 2 b.

(2) Formation of Anti-Reflecting Membrane on Front Plate

Refection occurs due to a difference between the refractive index of thefront plate and the refractive index of air. Therefore, a liquid crystaldisplay is provided which has a structure shown in FIG. 3A wherein ananti-reflecting membrane 11 is formed on the front plate, to reducereflection, and to improve visibility. In this case, it is desirable touse an anti-reflecting membrane made of an inorganic oxide, in order tosecure sufficient wear resistance.

FIG. 3B illustrates the case in which a polarizing plate is mounted tothe front plate. This case has the same effect as that of FIG. 1Bdescribed in association with Item 1.

(3) Formation of Anti-Reflecting Membranes at Both Sides of Front Plate

When the anti-reflecting membrane formation is carried out withoutmasking in accordance with dip coating, flow coating, or the like,anti-reflecting membranes are formed at both surfaces of the frontplate, respectively. Where the front plate is made of resin, it isdifficult to achieve filling of a transparent organic medium because thesurface hydrophilicity of the front plate is low. That is, penetrationof bubbles may easily occur, whereas escape of the penetrated bubbles isdifficult. Accordingly, an anti-reflecting membrane made of inorganicoxide is used to achieve an improvement in surface hydrophilicity. Thus,there is an effect capable of promoting the filling of the transparentorganic medium. Also, the close adherence of the polarizing platerequired when the polarizing plate is bonded can be enhanced by virtueof the improved surface hydrophilicity. The provision of anti-reflectingmembranes at the both surfaces of the front plate is shown in FIG. 4A.

FIG. 4B illustrates the case in which a polarizing plate is mounted tothe front plate. The effect obtained in this case is identical to thatof FIG. 1B described in association with Item 1.

(4) Holding of Liquid Crystal Module by Frame

In the case of a personal computer monitor or liquid crystal television,which is currently commercially available, all the backlight unit,polarizing plate, and liquid crystal cell thereof are held by a frame,together with the outer polarizing plate, as shown in FIG. 5A. To thisstructure, the controller, power supply unit, and outside frame aremounted, to enable the resulting structure to function as an imagedisplay device. Since the transparent organic medium layer and frontplate may be mounted after complete manufacture of the liquid crystalmodule, there is an advantage in that it is unnecessary to vary theexisting process for manufacturing the liquid crystal module.

FIG. 5B illustrates the case in which a polarizing plate is mounted tothe front plate. The effect obtained in this case is identical to thatof FIG. 1B described in association with Item 1.

The polarizing plates, liquid crystal cell, and backlight unit are shownin detail in FIGS. 6A and 6B, or FIGS. 7A and 7B. In this case, a driverIC 13 for controlling LED is arranged beneath the liquid crystal cell,and is connected to a flexible printed circuit (FPC) board 14. Thebacklight unit and liquid crystal panel are received in a backlightunit/liquid crystal panel housing 15. A reflecting layer 16 is coatedover an inner surface of the housing 15. The reflecting layer 16reflects light emitted from a fluorescent layer 17, to enable light tobe used for display of an image as much as possible. Light advancingfrom fluorescent tubes toward an image display surface first passesthrough a diffusing plate, so that the light is diffused. Thereafter,the light is incident to the liquid crystal cell after passing throughoptical sheets such as a diffusing sheet 19 and a prism sheet 20.Meanwhile, in this case, a top cover 21 is provided for the housing, inorder to prevent the liquid crystal cell from moving.

The driver IC for controlling LCD has a drain function. When thebacklight is turned on for a prolonged period of time, the liquidcrystal panel is heated by heat generated during the ON state of thebacklight. In this case, the top portion of the liquid crystal panel isgreatly heated, as compared to other portions of the liquid crystalpanel, so that the temperature thereof is greatly increased. If thedriver IC for controlling LCD is coupled to the top portion of theliquid crystal panel, damage of elements thereof caused by heat isincreased because the driver IC for controlling LCD is greatly heated.As a result, the durability of the panel is degraded. Even when there isno damage of elements, heat is transferred to the liquid crystal cell.For this reason, there may be a problem in that the image displayedthrough the liquid crystal cell may be dimmed when the liquid crystalcell is heated over the operational temperature of liquid crystals. Forthis reason, it is ideal that the driver IC for controlling LCD isarranged beneath the liquid crystal cell. However, where the driver ICfor controlling LCD is arranged beneath the liquid crystal cell, as inthe conventional liquid crystal display, there may be a possibilitythat, when the liquid crystal display is wiped using a wet duster, watermay be penetrated into the polarizing plate via the image displaysurface, and then, into the driver IC for controlling LCD. As a result,a short circuit may be generated. For this reason, taking intoconsideration the normal handling of the device by the user, it isnecessary to provide an appropriate watertight effect for thearrangement of the driver IC for controlling LCD beneath the liquidcrystal cell. In the above-described case, watertightness is obtained inaccordance with the provision of the front plate. Accordingly, it ispossible to arrange the driver IC for controlling LCD beneath the liquidcrystal cell. Thus, the driver IC for controlling LCD and liquid crystalpanel can have an extend life span.

FIGS. 8A and 8B illustrate a structure different from that of FIG. 7 interms of the number and configuration of optical sheets including atleast one diffusing sheet and at least one prism sheet arranged betweenthe backlight and the outer polarizing plate or liquid crystal cell. Inthe design of the display device, a desired number and desiredconfigurations of the optical sheets are appropriately selected inaccordance with the performance of the used diffusing plate or platesand the diffusion properties of the backlight.

In the cases of FIGS. 6 a to 8 b, fluorescent tubes are used. In FIG. 9,a configuration using light emitting diodes 22 (in some cases, alsoreferred to as “LEDs”) is illustrated. Each light emitting diode 22includes a light emitting portion 23, and a reflecting surface 24arranged around the light emitting portion 23. In the design of thedisplay device, one or both of the fluorescent tube configuration andlight emitting diode configuration are appropriately selected.

(5) Holding of Liquid Crystal Module from Backlight Unit to Front Plateby Frame

In the case of a personal computer monitor or liquid crystal television,which are currently commercially available, a controller, a power supplyunit, and an outer frame are mounted to a liquid crystal module (all thebacklight unit, polarizing plate, and liquid crystal cell of the liquidcrystal module are held by a frame, together with the outer polarizingplate, as shown in FIG. 5A), in order to enable the resulting structureto function as an image display device. Since even the transparentorganic medium layer and front plate are held by the frame, as shown inFIG. 11A, there is an advantage in that it is possible to manufacture apersonal computer monitor or a liquid crystal television without varyingthe existing process for manufacturing the liquid crystal display.

FIG. 11B illustrates the case in which a polarizing plate is mounted tothe front plate. The effect obtained in this case is identical to thatof FIG. 1B described in association with Item 1.

(6) Fixing of Front Plate to Frame

In the case of FIG. 11 a or 11 b, even the front plate is held by theframe. For example, in the case of a 32-inch liquid crystal television(TV), the front plate has a weight of about 1.5 Kg by itself when it isformed of a glass sheet having a thickness of 2 mm. When the front plateis fabricated using a glass sheet having a thickness of 3 mm, it mayhave a weight of about 2.2 Kg. For this reason, the frame, which holdsthe front plate, is required to use a frame member thicker than those ofconventional cases. However, this is undesirable because the weight ofthe liquid crystal TV is also increased.

When the front plate is fixed to the frame, as shown in FIG. 12A, it ispossible to not only support the frame, but also to support othermembers along with the front plate. In this case, accordingly, it isunnecessary to increase the thickness of the frame. That is, it ispossible to reduce the material amount of the used frame, and thus, tocorrespondingly reduce the costs. Since the thickness of the frame isreduced, there is also an advantage of easy workability.

FIG. 12B illustrates the case in which a polarizing plate is mounted tothe front plate. The effect obtained in this case is identical to thatof FIG. 1B described in association with Item 1.

(7) Support of Polarizing Plate and Liquid Crystal Cell by TransparentOrganic Medium Layer

As shown in FIGS. 13A and 14 a, the polarizing plate and liquid crystalcell are supported by a transparent organic medium layer, and all themembers are supported by the front plate. In this case, accordingly,only the backlight is supported by the frame. For this reason, it ispossible to reduce the thickness of the frame, as compared to the casedescribed in association with Item 6. That is, it is possible to furtherreduce the material amount of the used frame, and thus, tocorrespondingly reduce the costs. Since the thickness of the frame isfurther reduced, there is also an advantage of easier workability.

FIGS. 13 b and 14 b illustrate the cases in which a polarizing plate ismounted to the front plate. The effect obtained in this case isidentical to that of FIG. 1B described in association with Item 1.

[B] Constituent Unit, Members, Etc.

(1) Backlight Unit

The backlight unit includes a light source and optical sheets. The lightsource may include a cold cathode fluorescence lamp or LEDs. The opticalsheets may include a waveguide plate, a diffusing sheet, a prism sheet,and a reflecting and polarizing sheet.

(2) Polarizing Plate

The polarizing plate is a plate having a function for allowing only thelight with a specific vibration direction to be transmittedtherethrough. In the present invention, the polarizing plate is notparticularly limited. For the polarizing plate, those used inconventional liquid crystal displays may be used. Two polarizing platesare used in one display device. One polarizing plate is arranged betweenthe backlight unit and the liquid crystal layer. Although the otherpolarizing plate is arranged at different positions for different cases,the function of the polarizing plate itself can be achieved in any case.

(3) Liquid Crystal Cell

Generally, in a liquid crystal cell, a transparent electrode, analignment layer, a liquid crystal layer, another alignment layer, and acolor filter are held, in this order, between two glass substrates. Itis assumed that the liquid crystal cell of the present invention hasthis configuration. Other configurations may be used in the liquidcrystal display of the present invention, as long as they can achievethe same function as that of the above-described configuration.

(4) Front Plate

For the front plate, a transparent plate exhibiting no or littleabsorption of light of a visible range and high wear resistance isdesirable. Even when the front plate has high hardness, it may be easilyscratched if its surface is rough, when it is wiped by a duster withsharp particles or sand attached thereto. This is because the groovespresent in the surface of the front plate may be strongly wiped. Wherethe front plate is made of tri-acetyl cellulose, it may be easilyscratched because, although tri-acetyl cellulose has a pencil hardnessof 2 to 3H, as described above, it exhibits an arithmetic averageroughness Ra of 150 to 500 nm at the surface of the front plate inaccordance with anti-glaring.

Taking into consideration this fact, a glass plate having a pencilhardness of 9H or more, an acrylic resin plate having a pencil hardnessof 2H, or a tri-acetyl cellulose plate having a pencil hardness of 2 to3H may be used for the front plate. As described above, it is preferredthat the plate used for the front plate have a planar surface havingsmall-size irregularities, more particularly, an arithmetic averageroughness Ra of 100 nm or less, preferably, 10 nm or less.

Although the thickness of the front plate depends on the size of theliquid crystal display area, it is preferable to be 0.7 mm or more inthe case of the front plate made of glass, and to be 1 mm or more in thecase of the front plate made of resin such as acrylic resin. When thefront plate has a smaller thickness, it may be deformed during themanufacture thereof. This deformation affects the evenness of thedisplay surface of the product.

The front plate may have a size larger than those of the transparentorganic medium layer, polarizing plates, liquid crystal cell, andbacklight unit, as shown in FIGS. 7A and 7B.

(5) Transparent Organic Medium

In the present invention, the transparent organic medium has a solid orliquid phase at normal temperature.

The transparent organic medium exhibits a reduced reflectance as it hasa refractive index more approximate to those of the front plate andpolarizing plates. As will be described hereinafter, the front plate hasa composition containing glass (refractive index of 1.05 to 1.54),acrylic resin (refractive index of 1.49), polyethylene terephthalate(PET) (refractive index of 1.56), and polycarbonate (refractive index of1.59).

Here, when it is assumed that the refractive index of the front plate is“n₀”, and the refractive index of the transparent organic medium is “n”,the reflectance R at the interface between the front plate and thetransparent organic medium can be derived using the following equation:R=[(n ₀ −n)/(n ₀ +n)]²

When there is no transparent organic medium inside the front plate, thatis, when the front plate is in contact with an air layer (refractiveindex of 1.0), reflection of about 3.7 to 5.2% occurs at the interfacebetween the front plate and the air layer.

The reflection is caused by the refractive index difference between thefront plate and air. Accordingly, it is possible to reduce reflection byfilling, in the air layer, a transparent medium having a refractiveindex approximate to that of the front plate, to substitute air with thetransparent medium.

Under the condition in which the front plate is directly exposed to thesun, a considerable improvement in visibility can be achieved if thereflectance of about 3.7 to 5.25% at the interface between the frontplate and the transparent organic medium can be reduced to about 0.5%.Refractive indexes enabling the reflectance at one surface of the frontplate to be reduced to about 0.5% in accordance with filling of atransparent organic medium can be derived using the above-describedequation. The derived refractive indexes are described in the followingTable 1.

TABLE 1 Refractive Refractive Index of |n₀ − n| Index of FrontTransparent (Difference Plate Organic Medium Reflectance between n₀ and(n₀) (n) (%) n) 1.48 1.28 0.53 0.20 1.48 1.38 0.12 0.10 1.48 1.18 0.850.25 1.54 1.34 0.48 0.20 1.59 1.39 0.50 0.21 1.48 1.70 0.48 0.22 1.541.77 0.48 0.23 1.59 1.83 0.49 0.24

Referring to the above table, it can be seen that, in order to reducethe reflectance to about 0.5%, it is preferred that the differencebetween the refractive index of the front plate and the refractive indexof the transparent organic medium be 0.2 or less.

Accordingly, when it is assumed that the refractive index of the frontplate is “n₀”, and the refractive index of the transparent organicmedium is “n”, the reflectance R at the interface between the frontplate and the transparent organic medium can be derived using thefollowing equation:n ₀−0.2<n<n ₀+0.2

For the transparent organic medium, the following may be used.

For a solid transparent organic medium, a thermosetting resin orphoto-curable resin, which will be polymerized in accordance withthermosetting or photo-curing of monomers, may be used. In addition, acompletely-polymerized thermoplastic resin may be used.

The thermosetting resin or photo-curable resin can fill a gap definedinside the front panel by filling a monomer, as described above, in thegap, and setting or curing the monomer in accordance with application ofappropriate heat or irradiation of light. Examples of monomers of theabove-described resins include a monomer having a polymerizable doublebond, a monomer polymerizable with another different monomer or apolymer, a monomer polymerizable by dehydration reaction, and a monomerpolymerizable by alcohol elimination reaction.

Examples of the monomer having a polymerizable double bond includestyrene, methyl methacrylate, ethyl methacrylate, propyl methacrylate,iso-propyl methacrylate, buthyl methacrylate, iso-buthyl methacrylate,hexyl methacrylate, octhyl methacrylate, 2-ethylhexyl methacrylate,decyl methacrylate, dodecyl methacrylate, methyl acrylate, ethylacrylate, propyl acrylate, iso-propyl acrylate, buthyl acrylate,iso-buthyl acrylate, hexyl acrylate, octhyl acrylate, 2-ehylhexylacrylate, decyl acrylate, and dodecyl acrylate. One or more of thesemonomers are used to form a transparent organic medium layer. Thesemonomers may also be co-polymerized with another polymer or monomer, toform a transparent organic medium layer. In this case, examples of thepolymer may include polyacrylic acid and polyvinyl alcohol. Examples ofthe monomer include ethylene glycol, propylene glycol, diethyleneglycol, 1,3-dihydroxycyclobutane, 1,4-dihydroxycyclohexane, and1,5-dihydroxycyclooctane, each of which has a hydroxyl group in themolecular structure thereof, and ethylene glycol monoglycidyl ether andethylene glycol diglycidyl ether, each of which has a glycidyl group ata terminal thereof.

Examples of the monomer polymerizable by dehydration reaction include amonomer having two or more hydroxyl groups or glycidyl groups, or two ormore amino groups at terminals thereof, and a monomer having two or morecarboxyl groups or carboxyl acid anhydride structures at terminalsthereof. An example of a polymer produced in accordance withpolymerization of monomers by dehydration reaction include a polymerproduced in accordance with polycondensation of the monomer having twoor more hydroxyl groups or glycidyl groups, or two or more amino groupsat terminals thereof, and the monomer having two or more carboxyl groupsor carboxyl acid anhydride structures at terminals thereof. Examples ofthe monomer having hydroxyl groups at terminals thereof include ethyleneglycol, propylene glycol, diethylene glycol, 1,3-dihydroxycyclobutane,1,4-dihydroxycyclohexane, 1,5-dihydroxycyclooctane, and polyethyleneglycol. Examples of the monomer having glycidyl groups at terminalsthereof include ethylene glycol monoglycidyl ether and ethylene glycoldiglycidyl ether. Examples of the monomer having amino groups atterminals thereof include ethylenediamine, 1,4-diaminobutane,1,6-diaminohexane, 1,4-diaminobenzene, 2,6-diaminonaphthalene, andmelamine. Examples of the monomer having carboxyl groups at terminalsthereof include adipic acid, 1,3-phthalic acid, 1,4-phthalic acid,fumaric acid, maleic acid, trimesic acid, and pyromellitic acid.Examples of the monomer having carboxyl acid anhydride structures atterminals thereof include maleic anhydride, phthalic anhydride,trimellitic anhydride, and pyromellitic anhydride. Examples of a monomerpolymerizable by alcohol elimination reaction include a compound havingan alkoxy silane group and a compound having an alkoxy titane group.Examples of the monomer polymerizable by alcohol elimination reactioninclude tetramethoxy silane, tetraethoxy silane, tetrapropoxy silane,tetrabuthoxy silane, methyl trimethoxy silane, ethyl trimethoxy silane,buthyl trimethoxy silane, methyl triethoxy silane, ethyl triethoxysilane, buthyl triethoxy silane, 3-aminopropyl triethoxy silane,3-chloropropyl triethoxy silane, and 3-glycidylpropyl triethoxy silane.

The transparent organic medium layer may have an improved impactbuffering function by using a high elastic material such aspolyisobutylene. It is preferred that the transparent organic mediumhave an elasticity ranging from hardness of 5 to hardness of 40 whenbeing measured in accordance with the rubber hardness measurementStandard JIS K 6253. It is more preferable that the elasticity rangesfrom hardness of 10 to hardness of 30. When the transparent organicmedium has hardness of less than 5, there may be a possibility that adegradation in reliability occurs when the front plate is held on theliquid crystal display for a prolonged period of time. On the otherhand, when the transparent organic medium has hardness of more than 40,it is likely to exhibit a degraded impact buffering effect.

Examples of a thermoplastic resin include polystyrene, styrene/acrylicresin, acrylic resin, polyester resin, polypropylene, andpolyisobuthylene. These are liquefied when being heated to Tg or more,in order to achieve easy filling thereof.

When the transparent organic medium is liquid, or when the monomer isliquid, the filling of the transparent organic medium is carried out inaccordance with the following method. First, a bank 25 is formed aroundthe members (the front plate or polarizing plate, and the liquid crystalcell) with which the transparent organic medium will come into contact.In the case of the transparent organic medium layer shown in FIGS. 1Aand 1B, FIGS. 3 a to 5 b, or FIGS. 11 a to 14 b, a bank is provided ifthe transparent organic medium layer is liquid, or if the monomer isliquid, even though not shown. Thereafter, injection of the transparentorganic medium is carried out. If bubbles are present in the injectedtransparent organic medium, they are removed by pressurizing orpressurizing/heating the transparent organic medium using an autoclaveor the like, applying vibrations to the transparent organic medium usinga vibrator or the like, or sucking the bubbles. This process isschematically shown in FIG. 15.

In order to achieve easy removal of bubbles, it is preferable to improvethe hydrophilicity of a surface with which lo the transparent organicmedium comes into contact. More particularly, this surface is a contactsurface of the front plate, polarizing plate, anti-reflecting membrane,or liquid crystal cell with which the transparent organic medium comesinto contact. When the contact surface has an improved hydrophilicity,the transparent organic medium can more easily adhere to the contactsurface, as compared to air. As a result, bubbles can more easilyescape. More particularly, it is preferred that the hydrophilicity basedon water correspond to a water contact angle of 20°. At thishydrophilicity, it is possible to fill the transparent organic mediumwhile substantially preventing penetration of bubbles. In order to morereliably reduce penetration of bubbles, it is preferred that the watercontact angle be 10° or less.

Where the bank covers the image display surface, a transparent member isused for the bank, in order to prevent the edge of the displayed imagefrom being invisible due to the bank. Where the bank does not cover theimage display surface, it is unnecessary for the bank to be transparent.In this case, it is desirable to use a black bank, in order to obtainincreased distinctness of the displayed image.

In addition, the size of the transparent organic medium layer may belarger than those of the polarizing plate and liquid crystal cell, asshown in FIGS. 13A and 13B.

Where the transparent organic medium is liquid, it is preferred that asolvent having a relatively high boiling point be used for the liquidcomponent of the transparent organic medium, in order to prevent theliquid component from being easily volatilized by heat emitted from theliquid crystal display. Examples of the solvent include alcohol (6carbons or more), diol (ethylene glycol, propylene glycol, etc.),hydrocarbon (10 carbons or more), ethylene glycol monoalkylether,ethylene glycol monoalkylester, diethylene glycol monoalkylether,diethylene glycol monoalkylester, triethylene glycol monoalkylether, andtriethylene glycol monoalkylester.

Preferably, the transparent organic medium layer has a thickness of atleast 0.1 mm, in order to secure a desired accuracy in the formation ofthe bank, or to enable easy escape of bubbles where the transparentorganic medium is liquid. When the thickness of the transparent organicmedium layer is excessive, the transparent organic medium layer isexcessively heavy, in particular, in the case of liquid. In this case,it is difficult for the bank to hold the liquid. For this reason, it ispreferred that the thickness of the transparent organic medium layerdoes not exceed 10 mm. In order to make the transparent organic mediumlayer have a constant thickness, a method may be used in whichtransparent particles (layer thickness control particles) 26 having adiameter approximately equal to a target thickness of the layer areused. In accordance with this method, the particles are put into thegap, in which the transparent organic medium will be filled, such thatthe particles do not overlap with one another, and then the transparentorganic medium is filled in the gap. By the particles, it is possible tocontrol the thickness of the transparent organic medium layer to be thetarget thickness. Hereinafter, the particles will be referred to as“layer thickness control particles”. The resulting structure obtained inaccordance with the above-described method is schematically illustratedin FIG. 16.

The layer thickness control can also be possible by filling thetransparent organic medium in a state of being mixed with the layerthickness control particles.

In addition, a photo-curable resin monomer, in which a pigment havingabsorption anisotropy is dissolved, may be contained in the transparentorganic medium layer. After the monomer is cured in accordance withirradiation of light polarized by a polarizer, the pigment has a lightabsorption axis. In this case, accordingly, the transparent organicmedium layer can function as an auxiliary polarizing plate. In thiscase, it is also possible to reduce leakage of light during a blackdisplay of the liquid crystals.

Since the pigment used in the color filter scatters light emitted fromthe light source, the scattered light may be leaked during the blackdisplay. For this reason, there may be a problem of a degradation incontrast. Such a contrast degradation can be reduced when a pigmentfunctioning to absorb scattered light is contained in the transparentorganic medium layer. When black is displayed in the liquid crystaldisplay, the color tone thereof inclines to blue. This is because thelight leakage in a wavelength range of 400 to 450 nm is larger thanthose in other wavelength ranges. Accordingly, when a pigment capable ofabsorbing light of 400 to 450 nm is contained in the transparent organicmedium layer, it is possible to reduce the inclination of the color toneto blue during the black display, and thus, to more distinctly displayblack. The present invention is not limited to the pigment. Inorganic ormetal nano-particles have a light absorption effect according to aquantum size effect thereof.

(6) Anti-Reflecting Membrane

Since the anti-reflecting membrane is arranged at the outermost surfaceportion of the image display surface of the liquid crystal display, itis preferred that the anti-reflecting membrane have high wearresistance. Accordingly, it is preferred that the anti-reflectingmembrane be made of an inorganic material, rather than an organicmaterial. Also, since the anti-reflecting membrane is exposed to air, itis preferred that the anti-reflecting membrane be made of a materialthat is difficult to be oxidized by oxygen, or a material which hasalready been oxidized.

In the case of an anti-reflecting membrane having a multilayerstructure, it is formed using a combination of a zirconium oxide havinga high refractive index (on the order of about 2.1), a magnesiumfluoride having a low refractive index (about 1.38), and a silicon oxidehaving a refractive index ranging between the reflective indexes (on theorder of about 1.5). In this case, there is an advantage that inpractice the anti-reflecting membrane has high wear resistance becauseit has a high pencil hardness of 8 to 9H where the front plate is madeof glass.

In the case of an anti-reflecting membrane having a single-layerstructure, it should have a refractive index lower than that of the baseplate associated therewith. It is preferred that this membrane be madeof an inorganic oxide having a high pencil hardness. In particular,examples of a preferred inorganic oxide include a silicon oxide having arelatively low refractive index, and a silicon oxide having a matrix ofa silicon compound having a hydrolysable residue while having poresformed therein. Of these silicon oxides, a silica sol is morepreferable. In this case, the anti-reflecting membrane is formed inaccordance with the following method. First, fine silicon oxideparticles and silica sol are dispersed and dissolved in water or analcohol-based solvent. The resulting mixture, namely, a paint 27 forformation of the anti-reflecting membrane, is coated over the frontplate, and then rapidly heated. As a result, the solvent is rapidlyevaporated, thereby causing bubbles 28 to be formed in the coating. Inthis state, the coating is completely solidified. Thus, ananti-reflecting membrane 30, in which pores 29 are present, is formed.This process is schematically illustrated in FIG. 17.

FIG. 18 shows a photograph of a cross-section of the anti-reflectingmembrane used in the present invention.

The base plate is an acrylic plate. A carbon layer is formed on the baseplate. Here, the carbon layer is formed to prevent a cross-sectionsample from being broken during preparation thereof for a measurement tobe carried out for the cross-section. The effects of the presentinvention can still be achieved even when the carbon layer is notformed. Referring to FIG. 17, it can be seen that several pores arepresent in the anti-reflecting membrane used in the present invention.By virtue of the pores, the refractive index of the membrane is lowerthan the refractive index of a general silicon oxide, namely, about 1.5.As the content of fine silicon oxide particles is increased, therefractive index of the membrane is likely to be reduced.

The shape of the pores is irregular. Accordingly, the size of the porescan be seen to be about 5 to 150 nm when the pores are observed alongthe longer axis thereof. In order to identify the pores, an elementpresence strength measurement was performed for portions with pores andportions without pores. The results of the measurement are described inFIG. 19.

Referring to FIG. 19, it can be seen that the portions with poresexhibit low element presence strengths for carbon, oxygen, silicon,etc., as compared to the portions without pores. Based on the elementpresent strengths, accordingly, it is possible to identify presence ofpores. The refractive index of the anti-reflecting membrane can becontrolled by varying the rate of the matrix of the membrane, namely,the silicon oxide (refractive index of about 1.5) present in themembrane, and rate of the pores (refractive index of about 1.0) presentin the membrane. More particularly, as the rate of the pores isincreased, the refractive index of the membrane is reduced. Since theevaporation of the solvent in the coating carried out during thethermosetting of the coating contributes to the formation of pores, itis also possible to control the formation of pores in accordance withthe boiling point of the used solvent and the temperature of thethermosetting carried out after coating of the paint over the baseplate. Referring to FIG. 8, the above-described tendency can be seen.That is, the pores are more densely formed in a relatively upper portion(portion near the outermost surface) of the anti-reflecting membrane. Itis considered that this tendency results from the fact that bubbles,which start to be formed within the paint on the base plate, rise to aregion in the vicinity of the surface of the paint in accordance withthermosetting, namely, heating. When anti-reflecting membranes havingdifferent thicknesses are formed using paints having the samecomposition, respectively, the thinner membrane will exhibit a lowerrefractive index under the same thermosetting condition, by virtue ofthe above-described tendency. That is, this is because pores are likelyto be formed in a region in the vicinity of the surface of theanti-reflecting membrane. In order to densely form pores not only in theregion in the vicinity of the surface of the anti-reflecting membrane,but also in the inner portion of the anti-reflecting membrane, a methodmay be used in which the anti-reflecting membrane is formed to have adouble-layer structure. In accordance with this method, it is possibleto further enhance the physical strength of the membrane because poresare formed not only in the region in the vicinity of the surface of themembrane, but also in the inner portion of the membrane.

In the above description, the method for forming the anti-reflectingmembrane using a silica sol as a silicon compound having a hydrolysableresidue has been proposed. The silica sol is transformed into siliconoxide while being heated. The formed silicon oxide exhibits a high lighttransmittance because it has a high transparency. Examples oftetraalkoxy silane used to form a silica sol include tetramethoxysilane, tetraethoxy silane, tetrapropoxy silane, tetra iso-propoxysilane, tetra iso-buthoxy silane, and tetrabuthoxy silane. In place ofalkoxy silane, a silicon compound having a chloro group, for example, asilicon tetrachloride, may be used.

Examples of a silicon compound having a hydrolysable residue, other thanthe silica sol, include compounds having an amino, chloro or mercaptogroup, other than tetraalkoxy silane. More particularly, they include3-aminopropyl triethoxy silane, 3-aminopropyl trimethoxy silane,N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, 3-chloropropyltrimethoxy silane, 3-chloropropyl methydimethoxy silane,3-mercaptopropyl trimethoxy silane, vinyltrimethoxy silane,vinyltriethoxy silane, 3-glycidylpropyl trimethoxy silane,3-glycidylpropyl methyldimethoxy silane, and 3-methacryloxypropyltrimethoxy silane.

Examples of fine inorganic oxide particles include colorless or whitefine particles of silicon, aluminum, titanium and cerium oxides. As tothe size of the particles, it is preferred that the shorter axis of theparticles be not more than the average thickness of the membrane, for animprovement in the evenness of the membrane. Of the above-describedoxides, a silicon oxide (refractive index of about 1.5 to 1.7 and analuminum oxide (refractive index of about 1.7 to 1.9), which have arelatively low refractive index, are preferable in that it is possibleto more easily obtain a membrane having a low refractive index. Inparticular, fine silicon oxide particles having a low refractive indexare more preferable.

When the fine silicon oxide particles are spherical, they preferablyhave an average particle size of 190 nm or less, in order to preventscattering of visible light (wavelength of 380 to 760 nm) incident tothe membrane. When larger particles are used, the membrane may be dimbecause of possible scattering of incident light. In this case,application of the membrane to displays may be unsuitable. Also, whenthe fine silicon oxide particles have a chain shape, they preferablyhave a thickness of 190 nm for the same reason as the above. Inaddition, an improvement in transparency is achieved at a smallerdiameter of the fine silicon oxide particles. For this reason, theaverage diameter of the particles is preferred to be 100 nm or less. Inthe present invention, the lower limit size of the fine silicon oxideparticles is about 9 nm, taking into consideration commerciallyavailable sizes. However, particles of lower sizes may be used, as longas they are well dispersed in the membrane.

Preferably, the target membrane thickness set in the formation of theanti-reflecting membrane is 60 to 190 nm. Theoretically, a minimumreflectance is obtained under the condition of “t=λ/4n” when it isassumed that “λ” is the wavelength of incident light, and “n” is therefractive index of a medium (transparent plate, or anti-reflectingmembrane of the present invention), which the incident light enters.

When incident light is visible light (wavelength: 380 to 760 nm), and amaterial having a refractive index in a range from that of air(refractive index of about 1.0) as a medium to that of the transparentglass plate of relatively high refractive index (about 1.7) is used forthe membrane, it is preferred that the minimum thickness of the membranebe 56 nm (380/(4×1.7)=56). At a membrane thickness of less than 56 nm,the membrane cannot sufficiently affect reflectance when the incidentlight has a wavelength in the visible range. Accordingly, it ispreferable to set the target minimum thickness at 60 nm, which isslightly larger than 56 nm, taking into consideration the membranethickness distribution in the formation of the coating. On the otherhand, it is preferred that the maximum thickness of the membrane be 190nm (760/(4×1.0)=190). Based on the above conditions, it is consideredthat the thickness of the membrane of the present invention ispreferably in a range from 60 to 190 nm.

(7) Liquid Repellent Layer

The anti-reflecting membrane, which is used in the present invention, isformed in accordance with thermosetting. The anti-reflecting membranewill have an improved fouling resistance when being coated with afluorine compound having liquid repellency. However, the layer of afluoride having liquid repellency should be sufficiently thin, in orderto prevent a deterioration in the anti-reflecting effect of themembrane. More particularly, when the thickness of the liquid-repellentlayer is 56 nm or less, it is possible to eliminate adverse effects onreflectance, as described above in conjunction with the thickness of theanti-reflecting membrane.

The layer of the fluoride having liquid repellency may be formed by oneof the following two methods.

(A) Coating Made of Fluoride Having Liquid Repellency

This method forms a coating made of a fluoride having liquid repellency.The coated membrane exhibits liquid repellency by virtue of the coating.However, the coating exhibits high resistance, thereby causing thesurface resistance of the anti-reflecting membrane to be increased. As aresult, dust or the like may be easily attached to the anti-reflectingmembrane. Furthermore, a degradation in wear resistance may possiblyoccur because the pencil hardness of the surface of the membrane dependson the hardness of the liquid-repellent coating (lower than that ofsilicon oxide). Examples of materials useful for forming theliquid-repellent layer include CYTOP (the product of Asahi GlassCompany) and INT304VC (the product of INT MATERIAL Co., Ltd.). Each ofthese materials is diluted with a solvent, coated on a plate, and thenheated to volatilize the solvent, in order to form a liquid-repellentcoating. The coating may be formed using a thermosetting process,depending on circumstances.

(B) Binding of Perfluoropolyether Compound or Perfluoroalkyl Compound

This method binds, to the anti-reflecting film, a perfluoropolyether orperfluoroalkyl compound having an alkoxy silane group able to be boundto a hydroxyl group at a terminal thereof. More specifically, thecompounds represented by Formula 1 can be bound to the anti-reflectingmembrane.[F{CF(CF₃)—CF₂O}_(n)—CF(CF₃)]—X—Si(OR)₃{F(CF₂CF₂CF₂O)_(n)}—X—Si(OR)₃{H(CF₂)_(n)}—Y—Si(OR)₃{F(CF₂)_(n)}—Y—Si(OR)₃  (Formula 1)

wherein, X is a site at which a perfluoropolyether chain and an alkoxysilane residue are bound to each other, Y is a site at which aperfluoroalkyl chain and an alkoxy silane residue are bound to eachother, and R is an alkyl group.

In this case, the used compounds do not completely cover theanti-reflecting membrane surface. Perfluoropolyether chains orperfluoroalkyl chains are distributed in places on the anti-reflectingmembrane, like grass growing on the ground. Since the compounds areincompletely coated on the surface of the anti-reflecting membrane, theresistance of the anti-reflecting membrane is not increased even afterthe coating of the compounds. Also, it is possible to prevent adegradation in the pencil hardness of the membrane.

In accordance with the formation of perfluoropolyether or perfluoroalkylchains on the surface of the membrane, an improvement in the lubricityof the membrane surface is achieved. Accordingly, the membrane can havea surface capable of reducing wear-caused physical damages thereon, andexhibiting high wear resistance.

As apparent from the above description, it is advantageous to use themethod using a perfluoropolyether or perfluoroalkyl compound having analkoxy silane group at a terminal thereof, for formation of aliquid-repellent layer, because it is possible to maintain the membranesurface at low resistance, and to improve the wear resistance of themembrane surface, in addition to fouling resistance. Hereinafter, aliquid-repellent agent and a method for forming a liquid-repellent filmwill be described.

(a) Liquid-Repellent Agent

In particular, examples of the perfluoropolyether or. perfluoroalkylcompound having an alkoxy silane group at a terminal thereof include thefollowing Compounds 1 to 12:F{CF(CF₃)—CF₂O}_(n)—CF(CF₃)—CONH—(CH₂)₃—Si(OCH₂CH₃)₃  (Formula 2)F{CF(CF₃)—CF₂O}_(n)—CF(CF₃)—CONH—(CH₂)₃—Si(OCH₃)₃  (Formula 3)F{CF₂CF₂CF₂O}_(n)—CF₂CF₂—CONH—(CH₂)₃—Si(OCH₂OCH₃)₃  (Formula 4)F{CF₂CF₂CF₂O}_(n)—CF₂CF₂—CONH—(CH₂)₃—Si(OCH₃)₃  (Formula 5)H(CF₂₎ ₆—CONH—(CH₂)₃—Si(OCH₂OCH₃)₃  (Formula 6)H(CF₂)₆—CONH—(CH₂)₃—Si(OCH₃)₃  (Formula 7)H(CF₂ ₎ ₈—CONH—(CH₂)₃—Si(OCH₂OCH₃)₃  (Formula 8)H(CF₂)₈—CONH—(CH₂)₃—Si(OCH₃)₃  (Formula 9)F(CF₂)₆—(CH₂)₂—Si(OCH₃)₃  (Formula 10)F(CF₂)₈—(CH₂)₂—Si(OCH₃)₃  (Formula 11)F(CF₂)₆—(CH₂)₂—Si(OCH₂OCH₃)₃  (Formula 12)F(CF₂)₈—(CH₂)₂—Si(OCH₂OCH₃)₃  (Formula 13)

Of these, Compounds 1 to 8 can be produced by synthesizing methods whichwill be described, below. Compounds 9 to 12 are commercially availablefrom Hydrus Chemical as 1H,1H,2H,2H-perfluorooctyltrimethoxy silane,1H,1H,2H,2H-perfluorooctyltriethoxy silane,1H,1H,2H,2H-perfluorodecyltrimethoxy silane,1H,1H,2H,2H-perfluorodecyltriethoxy silane, respectively. DaikinIndustries' OPTOOL DSX is another commercially-available product. Eachof Compounds 1 to 4 has a fluorine chain which is perfluoropolyether.The liquid-repellent film formed of the compound having the fluorinechain exhibits little deterioration in liquid repellency (by 5° or less)even when immersed in a liquid other than water, for example, engine oilor gasoline, for a prolonged period of time (1,000 hours). Theliquid-repellent film is also advantageous in terms of foulingresistance. These compounds are represented by the following generalformula:[F{CF(CF₃)—CF₂O}_(n)—CF(CF₃)]—X—Si(OR)₃   (Formula 14){F(CF₂CF₂CF₂O)}_(n)—X—Si(OR)₃

wherein, X is a site at which a perfluoropolyether chain and an alkoxysilane residue are bound to each other, and R is an alkyl group.

When Compounds 5 to 12 are immersed in engine oil or gasoline for aprolonged period of time (1,000 hours), they show a contact angledecreased from a contact angle before immersion (about 110°) to almostthe contact angle of the base plate.

(Synthesis of Compound 1)

First, DuPont's Krytox 157FS-L (average molecular weight of 2,500) (25parts by weight) was dissolved in 3M's PF-5080 (100 parts by weight), towhich thionyl chloride (20 parts by weight) was added. The resultingmixture was heated under reflux for 48 hours while being stirred. Thethionyl chloride and PF-5080 were then removed by an evaporator, toproduce acid chloride of Krytox 157FS-L (25 parts by weight). To theproduct, PF-5080 (100 parts by weight), Chisso's Sila-Ace S330 (3 partsby weight), and triethyl amine (3 parts by weight) were added. Theresulting mixture was stirred at room temperature for 20 hours. Thereaction solution was filtered with a Showa Chemical Industry'sfiltration aid RADIOLITE FINE FLOW A, and PF-5080 was removed from thefiltrate by an evaporator, to produce Compound 1 (20 parts by weight).

(Synthesis of Compound 2)

Compound 2 (20 parts by weight) was produced in accordance with the samesynthesis as that of Compound 1, except that Chisso's Sila-Ace S330 (3parts by weight) was replaced by Chisso's Sila-Ace S360 (3 parts byweight).

(Synthesis of Compound 3)

Compound 3 (30 parts by weight) was produced in accordance with the samesynthesis as that of Compound 1, except that DuPont's Krytox 157FS-L(average molecular weight of 2,500) (25 parts by weight) was replaced byDaikin Industries' DEMNUM SH (average molecular weight of 3,500) (35parts by weight).

(Synthesis of Compound 4)

Compound 4 (30 parts by weight) was produced in accordance with the samesynthesis as that of Compound 1, except that Chisso's Sila-Ace S330 (3parts by weight) was replaced by Chisso 's Sila-Ace S360 (3 parts byweight) and DuPont's Krytox 157FS-L (average molecular weight of 2,500)(25 parts by weight) was replaced by Daikin Industries' DEMNUM SH(average molecular weight of 3,500) (35 parts by weight).

(Synthesis of Compound 5)

Compound 5 (3.5 parts by weight) was produced in accordance with thesame synthesis as that of Compound 1, except that DuPont's Krytox157FS-L (average molecular weight of 2,500) (25 parts by weight) wasreplaced by Daikin Industries' 7H-dodecafluoroheptanoic acid (averagemolecular weight of 346.06) (3.5 parts by weight).

(Synthesis of Compound 6)

Compound 6 (3.5 parts by weight) was produced in accordance with thesame synthesis as that of Compound 1, except that DuPont's Krytox157FS-L (average molecular weight of 2,500) (25 parts by weight) wasreplaced by Daikin Industries' 7H-dodecafluoroheptanoic acid (averagemolecular weight of 346.06) (3.5 parts by weight) and Chisso's Sila-AceS330 (2 parts by weight) was replaced by Chisso's Sila-Ace S320 (2 partsby weight).

(Synthesis of Compound 7)

Compound 7 (4.5 parts by weight) was produced in accordance with thesame synthesis as that of Compound 1, except that DuPont's Krytox157FS-L (average molecular weight of 2,500) (25 parts by weight) wasreplaced by Daikin Industries' 9H-hexadecafluorononanoic acid (averagemolecular weight of 446.07) (4.5 parts by weight).

(Synthesis of Compound 8)

Compound 8 (4.5 parts by weight) was produced in accordance with thesame synthesis as that of Compound 1, except that DuPont's Krytox157FS-L (average molecular weight of 2,500) (25 parts by weight) wasreplaced by Daikin Industries' Daikin Industries'9H-hexadecafluorononanoic acid (average molecular weight of 446.07) (4.5parts by weight) and Chisso's Sila-Ace S330 (2 parts by weight) wasreplaced by Chisso's Sila-Ace S320 (2 parts by weight).

(b) Method for Forming Liquid-Repellent Film

The method for forming a liquid-repellent film using aperfluoropolyether or perfluoroalkyl compound having an alkoxy silanegroup at a terminal thereof will be described.

First, a perfluoropolyether or perfluoroalkyl compound having an alkoxysilane group at a terminal thereof is dissolved in a solvent. Theconcentration of the resulting solution is generally in a range fromabout 0.01 to 1.0% by weight, even though it depends on the coatingmethod used. The alkoxy silane group is gradually hydrolyzed by water inthe solvent, or even by moisture absorbed from air into the solvent.Accordingly, it is preferable to dehydrate the solvent, or to select asolvent that is difficult to dissolve in water, such as a fluorine-basedsolvent. Examples of the fluorine-based solvent include 3M's FC-72,FC-77, PF-5060, PF-5080,HFE-7100 and HFE-7200, and DuPont's Vertrel XF.Thus, a solution, in which the perfluoropolyether or perfluoroalkylcompound is dissolved, is prepared (Hereinafter, the solution will bereferred to as a “liquid-repellent agent”.).

Thereafter, the liquid-repellent agent is coated on the anti-reflectingmembrane. The coating is carried out using a general coating method, forexample, dip coating or spin coating. Next, heating is performed. Theheating is required to enable the alkoxy silane residue to be bound tothe hydroxyl group on the membrane surface. Typically, the heating iscarried out at 120° C. for about 10 minutes, or at 100° C. for about 30minutes. At 90° C., the heating is carried out for about 1 hour.Although the heating may be carried out at normal temperature, aconsiderable time is required in this case.

Finally, the membrane surface is rinsed using a fluorine-based solvent,to remove the surplus liquid-repellent agent. Thus, the liquid-repellingtreatment is completed. For the solvent used in the rinsing process,solvents proposed in the description of the liquid-repellent agent maybe used.

The present invention is described in detail through examples. However,it is to be understood that scope of the present is not limited to theexamples.

EXAMPLE 1

Three sheets of liquid crystal modules each having a structure, in whicha polarizing plate, a liquid crystal cell, and another polarizing plateare arranged over a backlight unit in an overlapped manner, wereprepared. On one sheet, a glass plate having a thickness of 2 mm wasprovided, as a front plate, such that a layer of polyisobutylene as atransparent organic medium is interposed between the liquid crystalmodule and the glass plate. The polyisobutylene has a thickness of about1 mm. On another sheet, the same glass plate was provided, withoutfilling of polyisobutylene, such that an air layer is interposed betweenthe liquid crystal module and the glass plate. The liquid crystal moduleof the remaining one sheet was maintained as it is.

After measurement of pencil hardness at a load of 1 Kg for the surfacesof the modules, the modules having the front plate were not scratched bya 2H pencil, but the module having no front plate was scratched by the2H pencil. Accordingly, it was seen that it is possible to secure apencil hardness of 2H, and to achieve an improvement in wear resistanceby providing the front plate. Measurement of pencil hardness for thecases provided with the front plate using a pencil of a higher hardnessshowed that either the case provided with the transparent organic mediumor the case provided with no transparent organic medium exhibits apencil hardness of 9H or more.

Comparison between the modules each having the front plate showed thatthe case filled with no polyisobutylene exhibits increased reflection atthe surface thereof. In detail, the case filled with no polyisobutylenewas measured to have a reflectance of about 8%, whereas the case filledwith polyisobutylene was measured to have a reflectance of about 4%.Accordingly, it was seen that it is possible to reduce reflection byfilling polyisobutylene in the gap defined between the front plate andthe polarizing plate.

Both cases, in which respective polyisobutylene layers were formed tohave thicknesses of about 0.1 mm and about 10 mm, exhibit a reflectanceof about 4%.

EXAMPLE 2

Three sheets of liquid crystal modules each having a structure, in whicha polarizing plate, a liquid crystal cell, and another polarizing plateare arranged over a backlight unit in an overlapped manner, wereprepared. Thereafter, a controller, a power supply unit, etc. weremounted to each liquid crystal module, to manufacture a liquid crystaldisplay as an image display device. In two of the three sets, a driverIC for controlling LCD was mounted beneath the liquid crystal cell. Inthe remaining one set, the driver IC for controlling LCD was mountedover the liquid crystal cell. In one of the sets, in which the driver ICfor controlling LCD was mounted beneath the liquid crystal cell, a glassplate having a thickness of 2 mm was provided, as a front plate, suchthat a layer of polyisobutylene as a transparent organic medium isinterposed between the liquid crystal display and the glass plate. Thepolyisobutylene has a thickness of about 1 mm.

The three liquid crystal display sets were continuously used for 3 hoursin a room at 40° C. As a result, dimming of an image occurred in thevicinity of a region where the driver IC for controlling LCD wasmounted, in the liquid crystal display in which the driver IC forcontrolling LCD was mounted over the liquid crystal cell.

During operation of the liquid crystal display, heat from the backlightheats the interior of the liquid crystal display. In particular, theupper portion of the liquid crystal display is more intensively heated.The driver IC for controlling LCD is also heated, and the heat from thedriver IC for controlling LCD is transferred to the liquid crystal cell.In the case of the liquid crystal display, in which the driver IC forcontrolling LCD is mounted over the liquid crystal cell, the liquidcrystals of the liquid crystal cells are heated to around theoperational temperature thereof by the heat transferred from the driverIC for controlling LCD to the liquid crystal cell. As a result, theliquid crystals cannot exhibit liquid crystal characteristics. It isconsidered that the above-described image dimming was caused by such aphenomenon.

In order to remove dust on the screen of each liquid crystal display, aweak-alkaline glass cleaner was sprayed on the screen, and the screenwas then wiped using a duster. As a result, in the liquid crystaldisplay, in which the driver IC for controlling LCD was set beneath theliquid crystal set, and no front plate was provided, the screen couldpartially not display an image. On the other hand, such a phenomenon didnot occur in the remaining two sets. After investigation, it could beseen that the glass cleaner sprayed on the screen reached the driver ICfor controlling LCD via a gap defined between the polarizing plate andthe frame, and wetted the driver IC for controlling LCD. It isconsidered that, due to such a phenomenon, the circuit wiring of thedriver IC for controlling LCD was short-circuited, so that the screencould partially not display an image. The same phenomenon occurred whenwater mixed with a detergent was used in place of the glass cleaner.

Thus, it could be seen that the liquid crystal display, in which thedriver IC for controlling LCD was set beneath the liquid crystal set,and the front plate was provided, was preferable, in order to preventthe liquid crystal display from exhibiting an image dimming phenomenoneven after being used for a prolonged period of time in ahigh-temperature room, and to enable the liquid crystal display to havea liquid tightness capable of allowing the liquid crystal display towithstand screen cleaning using a liquid such as a glass cleaner or adetergent-mixed liquid.

EXAMPLE 3

Measurement of pencil hardness and reflectance was performed in the samemanner as that of Example 1, except that a double-sided tape having awidth of 6 mm and a thickness of 1 mm was attached to the polarizingplate near the ends of the polarizing plate, to define a bank for thetransparent organic medium, and tri-ethylene glycol was filled as thetransparent organic medium. After the measurement, it was seen that thecases using the front plate exhibited a pencil hardness of 9H or more,and the case filled with tri-ethylene glycol exhibited a reflectance ofabout 4%.

EXAMPLE 4

First, a method for forming an anti-reflecting membrane on the frontplate will be described.

(1) Preparation of Anti-reflecting Paint

A paint for forming an anti-reflecting membrane (hereinafter, referredto as an “anti-reflecting paint”) was prepared by mixing a silica solsolution (kept acidic with phosphoric acid, and containing a solvent ofwater:ethanol (=1:4) and an alkoxy silane polymer (2.5% by weight)) (3parts by weight) as a binder and a silicon oxide dispersion (having aparticle size of 10 to 30 nm, and containing solids at 10% by weight)(12 parts by weight) as fine inorganic oxide particles with ethanol (60parts by weight). The prepared paint had a boiling point of 80° C.

(2) Formation of Anti-Reflecting Membrane

The paint was coated over the front plate, namely, the glass platehaving a thickness of 2 mm, using a spin coating process.

Immediately after the coating, the glass plate was put into aconstant-temperature bath kept at 160° C., and then was heated for 10minutes. As a result, the silica sol was transformed into silicon oxide.Thus, thermosetting of the paint was completed. Accordingly, formationof an anti-reflecting membrane on the surface of the glass plate wascompleted.

(3) Optical Evaluation Test

After measurement of the thickness and refractive index of theanti-reflecting membrane formed on the glass plate, it was seen that thethickness was 120 nm, and the refractive index was 1.33. Also, theluminous reflectance of the surface, on which the anti-reflectingmembrane was formed, was measured to be 1.5%. The thickness andrefractive index measurement was performed using an ellipsometermanufactured by Mizoziri Kogaku Kogyo (Model: DHA-OLK). The glass platecoated with no anti-reflecting membrane exhibited a reflectance of about4% at each surface thereof. Accordingly, it could be seen that themembrane of the present invention had an anti-reflecting function.

After observing the cross-section of the formed anti-reflecting membranein accordance with a TEM analysis, pores having a size of 5 to 150 nmwere found in the anti-reflecting membrane, as shown in FIG. 18.

(4) Manufacture of Liquid Crystal Display

A liquid crystal display, in which polyisobuthylene was used as atransparent organic medium, was manufactured in the same manner as thatof Example 1, except that the front plate formed with theabove-described anti-reflecting film was used.

(5) Evaluation of Pencil Hardness, Etc.

After performing measurement of pencil hardness in the same manner asthat of Example 1, it was seen that the front plate provided with theanti-reflecting membrane had a pencil hardness of 6H, which was animprovement over the case provided with no front plate, namely, the casein which the outermost surface thereof is the polarizing plate (H).

A reflectance of 1.5% was measured. Accordingly, it was seen that thereflectance reduction effect was improved over the case provided with nofront plate.

EXAMPLE 5

Anti-reflecting membranes were formed on both surfaces of the frontplate, respectively, in the same manner as that of Example 4, exceptthat the formation of the anti-reflecting membranes were performed usinga dip coating process, in place of the spin coating process. Using theresulting front plate, a liquid crystal display was manufactured underthe condition in which polyisobuthylene was used as a transparentorganic medium, as in Example 4. The case, in which anti-reflectingmembranes were provided at both surfaces of the front plate, exhibited aconsiderably reduced rate of generation of bubbles and easy manufacture,as compared to cases other than the above-described case. It isconsidered that this is because the anti-reflecting membranes have porestherein, and thus, have an improved hydrophilicity, thereby enabling afilling process involving no generation of bubbles.

In the case using the front plate provided with anti-reflectingmembranes at both surfaces thereof, accordingly, easy manufacture of theliquid crystal display was confirmed.

EXAMPLE 6

An anti-reflecting paint was prepared in the same manner as that ofExample 5, except that N-(2-aminoethyl)-3-aminopropyltriethoxy silane(Chisso's Sila-Ace S320) (0.1 parts by weight) was used in place of thesilica sol solution (3 parts by weight). Using this paint,anti-reflecting membranes were formed on the front plate. Thereafter, aliquid crystal display was manufactured in the same manner as that ofExample 1, using the resulting front plate, under the condition in whichpolyisobuthylene was used as a transparent organic medium.

The display exhibited a pencil hardness of 4H at the image displaysurface thereof, and a surface reflectance of 1.6%. Thus, the displaywas confirmed to have high wear resistance, as compared to conventionalcases.

EXAMPLE 7

This example is identical to Example 1, except that a solution ofmonomer of photo-curable acrylic resin containing 0.1% of a pigment NK3981 (manufactured by Hayashibara Biochemical Laboratories) was used forthe transparent organic medium, which is interposed between thepolarizing plate arranged at the side of the observer of the liquidcrystal panel and the front plate formed with the anti-reflecting filmat the side of the observer. The acrylic resin monomer was cured inaccordance with irradiation of light of 365 nm thereto using ahigh-voltage mercury lamp.

In this example, the transparent organic medium functions as anabsorption layer having an absorption peak in the vicinity of awavelength of 490 nm by virtue of the effect of the pigment contained inthe transparent organic medium. Accordingly, an improvement in contrastratio can be expected.

The color filter used in the liquid crystal panel is formed with coloredlayers of blue, green, and red, using organic pigments. For example,PB15:6+PV23 is known for blue, PG36+PY150 is known for green, andPr177+PY83 is known for red. The organic pigments have a particle sizeof about 50 to 200 nm, and are present in a base polymer in a dispersedstate. However, they are of a particle system in a Rayleigh scatteringrange. For this reason, the organic pigments scatter incident light froma light source arranged at the back surface of the liquid crystal panel.The scattered light causes light leakage, thereby resulting in adegradation in contrast ratio. In the lo liquid crystal display, thisphenomenon is more serious in that the light incident to the liquidcrystal panel is not parallel light, but diffused light, because theliquid crystal panel has viewing angle properties.

Since the scattered light of the color filter is caused by Rayleighscattering, it has a peak at a wavelength shorter than the intrinsicspectral characteristics thereof. In particular, in the green filter,the peak wavelength thereof is shifted to a shorter wavelength, namely,from 530 nm to around 490 nm. The shifted peak wavelength is within thewavelength range of light emitted from the light source. The shiftedpeak wavelength is also within a wavelength range exhibiting arelatively high luminous sensitivity. For example, in the case of alight source using narrow-band light emitting phosphors, sub lightemitted from green phosphors is present in the vicinity of 490 nm. Inthe case of a light emitting diode, the peak of the light emitted fromthe light emitting diode does not correspond to the wavelength of 490nm. However, the wavelength of 490 nm is within the light emitting rangeof a blue or green light emitting diode. That is, light of 490 nm isunusually strengthened in a black display.

In this example, the function for absorbing light of around 490 nm isprovided to the transparent organic medium. In accordance with thisfunction, it is possible to absorb unnecessary light of around 490 nmunusually pronounced in a black display. On the other hand, in a whitedisplay, the intensity of light around 490 nm is very weak. Accordingly,although light of this wavelength is absorbed, a contrast ratioimprovement effect can be obtained because there is no serious affect onthe intensity of light transmitted in a white display. In this example,it was possible to reduce the black-level transmittance by 13%, and toimprove the contrast ratio by 10% in accordance with the addition of thepigment in an amount of 0.1 wt %.

In order to enable the transparent organic medium to function as anabsorption layer, a pigment is preferable which has an absorption peakin the vicinity of 490 nm, and can be dispersed in the transparentorganic medium. Of course, the pigment is not limited to this example.The addition amount of the pigment can be appropriately optimized,taking into consideration the absorbance of the used pigment, theblack-level transmittance, and the white-level transmittance.

EXAMPLE 8

This embodiment is identical to Example 6, except that the transparentorganic medium was replaced by a photo-curable acrylic resin added with0.2 wt % of metal nano-particles. In this example, it is possible toabsorb unusual components of scattered light in the vicinity of about490 nm by the pigment of the color filter during a black display, andthus, to achieve an improvement in contrast ratio. It is also possibleto uniformly disperse the metal nano-particles in the organic medium bysurface-treating the metal nano-particles, using a surfactant, toprevent cohesion of the nano-particles. In this example, 0.2 wt % ofgold nano-particles having a particle size of 10 nm or less,surface-treated by a surfactant, for example, an acrylic and mercaptogroup containing long hydrocarbon compound, was added to and mixed withthe resin. As a result, it was possible to reduce the black-leveltransmittance by 10%, and thus, to improve the contrast ratio by 8%.

For the metal nano-particles, various metal nano-particles may be used,as long as they have an absorption peak in the vicinity of 490 nm, andcan be uniformly dispersed in the organic medium after surface treatmentthereof. Nano-particles made of an alloy of various metals may also beused. Of course, the metal nano-particles are not limited to thisexample. The addition amount of the nano-particles can be appropriatelyoptimized, taking into consideration the absorption coefficient of theused particles, the black-level transmittance, and the white-leveltransmittance.

EXAMPLE 9

This example is identical to Example 7, except that the transparentorganic medium was replaced by a photo-curable acrylic resin added with0.1 wt % of 4-carboxymethylazobenzene, and the light irradiation processfor photo-curing was replaced by another one. In order to develop anabsorption anisotropy before photo-curing the acrylic resin, ahigh-voltage mercury lamp was used as the light source. Using aninterference filter, i-rays of 365 nm were obtained. The i-rays werethen irradiated to the base plate with irradiation energy of about 5J/cm2, in the form of linear polarized light having a polarization ratioof about 10:1, using a pile polarizer having a laminate of quartzplates. The polarization direction of the irradiated polarized lightcorresponded to the shorter-side direction of the base plate.Thereafter, ultraviolet rays in a range of 250 to 450 nm were irradiatedto the entire surface of the base plate, in order to photo-cure thetransparent organic medium, namely, the acrylic resin. The two rays maybe irradiated in a merged state. In accordance with the irradiation ofthe rays, the transparent organic medium developed an absorption axis inthe longer-side direction of the base plate. This is because thedeveloped absorption axis should extend in the same direction as theabsorption axis of the polarizing plate on the front surface of theliquid crystal panel used in this example, namely, the polarizing platearranged at the side of the observer. When the absorption axis of thefront polarizing plate of the used liquid crystal panel extends in ashorter-side direction, the polarization plane of the irradiatedpolarized light is changed to correspond to the longer-side direction ofthe base plate. In this example, a material was used which causesdevelopment of an absorption axis in a direction orthogonal to thepolarization direction of the irradiated polarized light. However, wherea different material is used which causes development of an absorptionaxis in the same direction as the polarization plane of the irradiatedpolarized light, for example, photo-oxidation in the polarizationdirection of the irradiated polarized light, the polarization directionof the irradiated polarized light may be appropriately changed. The sameeffect can be obtained in accordance with linear irradiation other thanirradiation using the polarizer, as long as the used material is aphoto-functional material capable of developing uniaxial absorptionanisotropy. The photo-functional material is not limited to thecompounds in this example. The addition amount of the usedphoto-functional material can be appropriately optimized in accordancewith the capability of the photo-functional material to developanisotropy.

Since the transparent organic medium used in this example functions asan assistant polarizing plate for the observer-side polarizing plate, itis possible to effectively reduce light leakage in a black display, evenwhen the developed uniaxial absorption anisotropy is slight.Accordingly, an improvement in contrast ratio can be achieved. In thisexample, it was possible to reduce the black-level brightness by 5%, andthus, to improve the contrast ratio by 5%.

EXAMPLE 10

This embodiment is identical to Example 8, except that the transparentorganic medium was replaced by a photo-curable acrylic resin added with0.12 wt % of DIRECT ORANGE 39. The transparent organic medium used inthis example exhibits dichroism at wavelengths of 400 to 500 nm.Accordingly, in a black display, it is possible to efficiently absorbleaked light of high intensity in a short-wavelength range. Also, thereis no affect on a white display. As a result, in this example, animprovement contrast ratio and correction of black-level color toneswere possible. Various pigments may be added, as long as they exhibitdichroism, and can be added to the transparent organic medium.

Generally, in a liquid crystal display, the inclination of black-levelcolor tones to blue is higher than that of white-level color tones. Thisis because the degree of polarization of the polarizing plate depends onwavelengths, and because light leakage is increased in a wavelengthrange of 400 to 450 nm. In this example, it was possible to absorbleaked light of 400 to 450 nm in a black display by the transparentorganic medium containing the dichromatic pigment. Black-level colortones approximated to an achromatic color. The contrast ratio could beimproved by 3%.

EXAMPLE 11

In this example, a liquid crystal display was manufactured in the samemanner as that of Example 4, except that an acrylic resin plate having athickness of 2 mm was used in place of the glass plate having athickness of 2 mm.

As a result, the anti-reflecting membrane on the surface of the acrylicresin plate had a thickness of 115 nm and a refractive index of 1.33.Also, the luminous reflectance of the surface, on which theanti-reflecting membrane was formed, was 1.5%. The acrylic resin platecoated with no anti-reflecting membrane exhibited a reflectance of about4%. Accordingly, a reflectance reduction effect was confirmed, ascompared to the front plate.

A pencil hardness of 4H was measured. That is, an improvement inhardness was exhibited, as compared to the polarizing plate (H). Also,an improvement in hardness was exhibited, as compared to the acrylicresin plate formed with no anti-reflecting membrane (2H).

The same results were obtained in the case in which a photo-curableacrylic resin is used, as the transparent organic medium, in place ofpolyisobuthylene. Since filling of the used photo-curable acrylic resinwas carried out under the condition in which the monomer of the acrylicresin slightly dissolved the acrylic resin plate, the formation ofbubbles in the transparent organic medium layer was likely to bereduced.

EXAMPLE 12

In this example, a liquid crystal display was manufactured in the samemanner as that of Example 4, except that a polycarbonate plate having athickness of 2 mm was used in place of the glass plate having athickness of 2 mm.

As a result, the anti-reflecting membrane on the surface of thepolycarbonate plate had a thickness of 115 nm and a refractive index of1.33. Also, the luminous reflectance of the surface, on which theanti-reflecting membrane was formed, was 1.5%. The polycarbonate platecoated with no anti-reflecting membrane exhibited a reflectance of about4%. Accordingly, a reflectance reduction effect was confirmed, ascompared to the front plate.

A pencil hardness of 3H was measured. That is, an improvement inhardness was exhibited, as compared to the polarizing plate (H). Also,an improvement in hardness was exhibited, as compared to thepolycarbonate plate formed with no anti-reflecting membrane (2B).

The same results were obtained in the case in which a photo-curableacrylic resin is used, as the transparent organic medium, in place ofpolyisobuthylene. Since filling of the used photo-curable acrylic resinwas carried out under the condition in which the monomer of the acrylicresin slightly dissolved the acrylic resin plate, the formation ofbubbles in the transparent organic medium layer was likely to bereduced.

EXAMPLE 13

A liquid-repelling treatment was performed for the front plate formedwith the anti-reflecting membrane, which was prepared in Example 4.

(1) Preparation of Liquid-Repellent Solution

First, 0.1 wt % solutions of Compounds 1 to 12 (solvent: 3M'sPF-5080)were prepared as liquid-repellent solutions. The 0.1 wt % PF-5080solution of Compound 1 is referred to as a “liquid-repellent solution[1]”, the 0.1 wt % PF-5080 solution of Compound 2 is referred to as a“liquid-repellent solution [2]”, . . . , and the 0.1 wt % PF-5080solution of Compound 12 is referred to as a “liquid-repellent solution[12]”.

Next, for comparison, a 0.1% PF-5080 solution of Cytop CTX-109Amanufactured by ASAHI GLASS COMPANY was used as a liquid-repellentsolution [13].

(2) Liquid-repelling Treatment

the case using the liquid-repellent solutions [1] to [12].

The liquid-repellent solution is coated over the front plate, using abrush. The front plate is then maintained for 30 minutes in aconstant-temperature bath, the interior of which has been heated to 95°C. Thereafter, the front plate is taken out of the constant-temperaturebath, and the surface of the front plate is then rinsed using PF-5080,to remove the surplus liquid-repellent solution. Thus, the treatment iscompleted.

the case using the liquid-repellent solution [13]

The liquid-repellent solution is coated over the front plate, using abrush. The front plate is then maintained for 90 minutes in aconstant-temperature bath, the interior of which has been heated to 95°C. Thereafter, the front plate is taken out of the constant-temperaturebath. Thus, the treatment is completed.

(3) Evaluation of Liquid Repellency

The liquid repellency of the base plate surface, for which theliquid-repelling treatment was completed, was evaluated, based on awater contact angle. The evaluation results are described in Table 2.

TABLE 2 Surface Resistivity of Liquid-Repelling Contact Front PlatePencil Treatment State Angle(°) (×10¹⁰ Ω) Hardness BeforeLiquid-Repelling Less 2 6 H Treatment Than 10 After [1] 112 2 6 HLiquid-Repelling [2] 112 2 6 H Treatment [3] 118 2 6 H [ ] is [4] 118 26 H liquid-repellent [5] 99 2 6 H solution No. [6] 100 2 6 H [7] 99 2 6H [8] 100 2 6 H [9] 105 2 6 H [10] 107 2 6 H [11] 105 2 6 H [12] 107 2 6H [13] 105 10° or more HFront plates prepared in Example 3 were used in the liquid-repellingtreatment.

The water contact angle before the liquid-repelling treatment, therefractive indexes, reflectances, and pencil hardnesses before and afterthe liquid-repelling treatment are also described.

Before the liquid-repelling treatment, all anti-reflecting filmsexhibited a water contact angle of 100 or less. After theliquid-repelling treatment, however, all anti-reflecting films exhibitedan increased water contact angle. Since there was no variation inrefractive index and reflectance between before and after theliquid-repelling treatment, it was confirmed that the liquid-repellingtreatment does not degrade performances associated with the refractiveindex and reflectance.

In the case, in which the liquid-repelling treatment was performed usingthe 0.1% solution of Cytop CTX-109A, the surface resistance of the frontplate was increased. It is considered that this is because, althoughCytop CTX-109A is substantially completely coated over the surface ofthe anti-reflecting membrane, the liquid-repellent fluorine-based chainin each of Compounds 1 to 12 is bound in places to the surface of theanti-reflecting membrane via the alkoxy silane group, that is, becauseeach of Compounds 1 to 12 is incompletely coated on the surface of theanti-reflecting membrane. When an increase in membrane resistanceoccurs, the membrane can be easily electrified. In this case, there is aproblem in that waste or dust may easily be attached to the membrane. Inthis regard, Compounds 1 to 12, which do not cause an increase inmembrane resistance, are preferable in that they maintain the membranein a state making it difficult for waste or dust to be attached to themembrane.

Thus, the fluorine-based compound having an alkoxy silane group at aterminal thereof was confirmed to be is suitable in that it does notincur an increase in membrane resistance in spite of the provision ofliquid repellency.

Next, as to the pencil hardness of the anti-reflecting membrane, all themembranes respectively subjected to a liquid-repelling treatment usingCompounds 1 to 12 exhibited a pencil hardness of 7H. However, themembrane treated with Cytop CTX-109A exhibited a pencil hardness of H.Since the pencil hardness before the liquid-repelling treatment was 6H,it was also apparent that an improvement in wear resistance was achievedin accordance with the liquid-repelling treatment using Compounds 1 to12.

After comparison of the compounds used in the liquid-repellingtreatment, it can be seen that the cases using Compounds 1 to 4 exhibita high contact angle. Although a minimum contact angle was exhibited inthe case treated using Compound 1 or 2, it was 110°. In particular, ahigher contact angle was exhibited in the cases using Compounds 3 and 4.In both cases, the contact angle was 115°. Compounds 1 to 4 have aperfluoropolyether chain. The remaining compounds have a perfluoroalkylchain or a fluoroalkyl chain. Accordingly, it could be seen that it ispossible to form a front plate having excellent liquid repellency whenthe liquid-repelling treatment is carried out using a compound having aperfluoropolyether chain.

1. A liquid crystal display comprising a backlight unit, a backlightunit-side polarizing plate, and a liquid crystal cell held by two glassplates, the liquid crystal cell having an electrode, a liquid crystallayer, an alignment layer, and a color filter arranged between the glassplates, the liquid crystal display further comprising: a transparentfront plate arranged at a side of the liquid crystal cell opposite tothe backlight unit; a polarizing plate attached to the liquid crystalcell; a transparent organic medium layer arranged between thetransparent front plate and the polarizing plate to reduce reflectionsat a backside of the front plate; and an anti-reflecting membranearranged at a side of the transparent front plate opposite to thetransparent organic medium layer; wherein a thickness of the transparentfront plate is at least 0.7 mm, and wherein the transparent organicmedium layer has a thickness of 0.1 mm to 10 mm.
 2. A liquid crystaldisplay comprising a backlight unit, a backlight unit-side polarizingplate, and a liquid crystal cell held by two glass plates, the liquidcrystal cell having an electrode, a liquid crystal layer, an alignmentlayer, and a color filter arranged between the glass plates, the liquidcrystal display further comprising: a transparent front plate arrangedat a side of the liquid crystal cell opposite to the backlight unit; atransparent organic medium layer arranged between the transparent frontplate and the liquid crystal cell; a polarizing plate attached to thetransparent front plate at a side of the transparent organic mediumlayer; and an anti-reflecting membrane arranged at a side of thetransparent front plate opposite to the transparent organic mediumlayer; wherein a thickness of the transparent front plate is at least0.7 mm , and wherein the transparent organic medium layer has athickness of 0.1 mm to 10 mm.
 3. The liquid crystal display according toany one of claims 1 and 2, wherein a driver IC for the liquid crystalcell is arranged under the liquid crystal cell.
 4. The liquid crystaldisplay according to any one of claims 1 and 2, wherein the front platehas an arithmetic average roughness (Ra) of 10 nm or less.
 5. The liquidcrystal display according to any one of claims 1 and 2, wherein thetransparent organic medium layer and the front plate have a refractiveindex relation satisfying the following equation:n ₀−0.2<n<n ₀+0.2 wherein, “n” represents a refractive index of a memberconstituting the transparent organic medium layer, and “n₀” represents arefractive index of the front plate.
 6. The liquid crystal displayaccording to any one of claims 1 and 2, wherein the transparent organicmedium layer contains a compound capable of absorbing light in a visiblerange.
 7. The liquid crystal display according to claim 6, wherein thecompound capable of absorbing light in a visible range is a compoundhaving a uniaxial anisotropy.
 8. The liquid crystal display according toany one of claims 1 and 2, wherein: the anti-reflecting membrane is madeof silicon oxide particles and a binder; and the anti-reflectingmembrane has pores formed in the anti-reflecting membrane.
 9. The liquidcrystal display according to any one of claims 1 and 2, wherein: theanti-reflecting membrane is made of silicon oxide particles and asilicon compound having a hydrolysable residue; and the anti-reflectingmembrane has pores formed in the anti-reflecting membrane.
 10. Theliquid crystal display according to any one of claims 1 and 2, whereinthe anti-reflecting membrane has a layer formed of a compound having aperfluoropolyether chain, a perfluoroalkyl chain, or a fluoroalkyl chainat a surface of the compound.
 11. The liquid crystal display deviceaccording to any one of claims 1 and 2, wherein the thickness of thetransparent front plate of at least 0.7 mm substantially preventsdeformation during manufacture and enables evenness of a display surfaceof the liquid crystal display.
 12. The liquid crystal display accordingto one of claims 1 and 2, wherein a bank is formed around the frontplate, the polarizing plate, or the liquid crystal cell.
 13. The liquidcrystal display according to claim 1, wherein the transparent organicmedium layer is comprised of a liquid, and wherein said liquid crystaldisplay includes means for enabling easy escape of bubbles from saidliquid, said means comprising setting the thickness of the transparentorganic medium layer to be 0.1 mm to 10 mm.
 14. The liquid crystaldisplay according to claim 2, wherein the transparent organic mediumlayer is comprised of a liquid, and wherein said liquid crystal displayincludes means for enabling easy escape of bubbles from said liquid,said means comprising setting the thickness of the transparent organicmedium layer to be 0.1 mm to 10 mm.
 15. A method for manufacturing aliquid crystal display including a backlight unit, a backlight unit-sidepolarizing plate, and a liquid crystal cell held by two glass plates,the liquid crystal cell having an electrode, a liquid crystal layer, analignment layer, and a color filter arranged between the glass plates, atransparent front plate arranged at a side of the liquid crystal cellopposite to the backlight unit, the transparent front plate having ananti-reflecting membrane at at least one surface of the transparentfront plate, a polarizing plate attached to the liquid crystal cell, anda transparent organic medium layer arranged between the front plate andthe polarizing plate to reduce reflections at a backside of the frontplate, the method comprising a step of: treating a surface of thepolarizing plate and a surface of the transparent front plate contactingthe transparent organic medium layer such that the surfaces have a watercontact angle of no more than 10° to reduce penetration of bubbles intothe transparent organic medium and to facilitate removal of bubbles fromthe transparent organic medium.
 16. The method according to claim 15,further comprising a step of providing the transparent front plate witha thickness of at least 0.7 mm.
 17. The method according to claim 16,wherein the thickness of the transparent front plate of at least 0.7 mmsubstantially prevents deformation during manufacture and enablesevenness of a display surface of the liquid crystal display.